Printed circuit boards are commonly used in electronic devices such as instruments, computers, telecommunication equipment and consumer electronic products. Typically, an engineer will design a printed circuit board to carry the types of components necessary to implement the desired electronic function and to fit in the space available for the board. Consequently, each printed circuit board typically is custom designed. To design a custom printed circuit board is expensive, takes time and requires the fabrication of prototype printed circuit boards. If errors are found in the prototypes, then the printed circuit board must be redesigned. Such a process often delays the planned introduction of a new product.
To alleviate this problem I invented a field programmable printed circuit board which is described in my above referenced copending patent application. In accordance with my invention described in the above referenced application, I provide a printed circuit board of unique configuration combined with one or more special programmable integrated circuit chips (hereinafter called "programmable interconnect chips" or "PICs") to provide a user programmable printed circuit board capable of being used to provide any one of a plurality of functions. As described in the above referenced application, in one embodiment of that invention, a field programmable printed circuit board comprises:
(1) a multiplicity of component contacts for receipt of the leads of electronic components;
(2) a corresponding multiplicity of PIC contacts for receipt of the leads on the package or packages of the programmable interconnect chip or chips; and
(3) one or more layers of conductive traces, each conductive trace uniquely connecting one component contact to one PIC contact.
Typically, electronic components comprise integrated circuits and/or discrete devices contained, respectively, in standard integrated circuit or discrete device packages and in addition, discrete elements which include resistors, capacitors and inductors, for example. As described in the above-mentioned application, each PIC contact brings a corresponding trace from a selected level on the PC board to the surface of the PC board so that trace is then connectable to a pin or electrical contact on a programmable interconnect chip. For every component contact (the function of which is to receive the pin or electrical contact of an electronic component) there is a corresponding electrically conductive trace which interconnects that component contact to a corresponding PIC contact (the function of which is to receive electrically contact pin or electrical contact of the programmable interconnect chip) in the printed circuit board. Thus, each component contact is electrically and uniquely connected to a corresponding PIC contact.
For printed circuit boards to be produced in high volume it is desirable to reduce the number of integrated circuit chips to be placed on the printed circuit board.